java.lang.reflect.Field的hashCode()方法用于获取此Field的哈希码。最终哈希码被计算为基础字段声明类名称及其名称的哈希码的异或。如果对象不变,则哈希码始终相同。哈希码是由JVM在对象创建时生成的唯一代码。它可用于对与哈希相关的算法(例如哈希表,哈希图等)执行某些操作。也可以使用此唯一代码搜索对象。
用法:
public int hashCode()
参数:此方法不接受任何内容。
返回值:此方法返回一个整数,该整数是此对象的哈希码值。
以下示例程序旨在说明hashCode()方法:
程序1:
// Java program to demonstrate hashCode() method
import java.lang.reflect.Field;
public class GFG {
public static void main(String[] args)
throws Exception
{
// Get the marks field object
Field field = User.class.getField("Marks");
// Apply hashCode Method on User Object
// to get the hashCode of Marks field
int value = field.hashCode();
// print result
System.out.println("HashCode of Marks field"
+ " is " + value);
// Now Get the Fees field object
field = User.class.getField("Fees");
// Apply hashCode Method on User Object
// to get the hashcode of Fees field
value = field.hashCode();
// print result
System.out.println("HashCode of Fees field"
+ " is " + value);
// Now Get the name field object
field = User.class.getField("name");
// Apply hashCode Method on User Object
// to get the hashCode of name field
value = field.hashCode();
// print result
System.out.println("HashCode of name field"
+ " is " + value);
}
}
// sample User class
class User {
// static double values
public static double Marks = 34.13;
public static float Fees = 3413.99f;
public static String name = "Aman";
public static double getMarks()
{
return Marks;
}
public static void setMarks(double marks)
{
Marks = marks;
}
public static float getFees()
{
return Fees;
}
public static void setFees(float fees)
{
Fees = fees;
}
public static String getName()
{
return name;
}
public static void setName(String name)
{
User.name = name;
}
}
输出:
HashCode of Marks field is 71482573 HashCode of Fees field is 591398 HashCode of name field is 1779040
程序2:
// Java program to demonstrate hashCode() method
import java.lang.reflect.Field;
import java.time.Month;
public class GFG {
public static void main(String[] args)
throws Exception
{
// Get all field objects of Month class
Field[] fields = Month.class.getFields();
for (int i = 0; i < fields.length; i++) {
// print name of Fields
System.out.println("HashCode of Field: "
+ fields[i].hashCode());
}
}
}
输出:
HashCode of Field: -297508095 HashCode of Field: 1296412905 HashCode of Field: 1475695976 HashCode of Field: 1343692077 HashCode of Field: 1404020238 HashCode of Field: 1401709321 HashCode of Field: 1401709395 HashCode of Field: 538235208 HashCode of Field: 2125827066 HashCode of Field: -1718938229 HashCode of Field: -1007182215 HashCode of Field: 59532142
参考文献: https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#hashCode-
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注:本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 Field hashCode() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。